In a fine processing using plasma for manufacturing semiconductor devices or flat panel displays (FPDs), the control of a temperature or temperature distribution of a processing target substrate (e.g., a semiconductor wafer or a glass substrate) is very important together with the control of a plasma density distribution on the processing target substrate. Unless the temperature control of the substrate is properly performed, uniformity of a substrate surface reaction or a process characteristic cannot be secured and thus, a manufacturing yield of semiconductor devices or display devices is reduced.
A mounting stage or a susceptor, on which a processing target substrate is mounted within a chamber of a plasma processing apparatus, in particular, a capacitively coupled plasma processing apparatus, generally has a high frequency electrode function for applying high frequency waves to a plasma space, a holder function for holding the substrate using, for example, electrostatic attraction, and a temperature controller function for controlling the substrate to a predetermined temperature with heat transfer. In connection with the temperature control function, it is requested that a distribution of heat input characteristic to a substrate which is caused by non-uniformity of radiant heat from plasma or a chamber wall, or a heat distribution caused by a substrate support structure be properly corrected.
Conventionally, in order to control the temperature of the susceptor and hence the temperature of the substrate, a heater system has been frequently used in which a heating element that generates heat by electrification is embedded in the susceptor and Joule heat generated by the heating element is controlled. However, when the heater system is adopted, the high frequency waves applied to the susceptor from the high frequency power supply are partially apt to enter a hater power feeding line from the heating element as noises. When the high frequency noises get out of the heater power feeding line and reach a heater power supply, the operation or performance of the heater power supply may be disturbed. In addition, when a high frequency current flows through the heater power feeding line, the high frequency power is wastefully consumed. Due to the problems described above, a filter is commonly provided on the heater power feeding line so as to attenuate or block the high frequency noise entering from the heating element embedded in the susceptor. Conventionally, this kind of filter is disposed just below the susceptor and outside the processing container.
In Patent Document 1, the assignee of the present application discloses a filter technique that improves the performance of a filter configured to cut off high frequency waves entering a power feeding line or a signal line from a high frequency electrode or any other electric member within a processing container in a plasma processing apparatus. The filter technique completes a coil contained within the filter using one air core coil by using a regular multiple parallel resonance characteristic.